The invention specifically pertains to an improvement in fall protection devices of the type described in U.S. Pat. Nos. 3,335,469 and 3,948,362 the disclosure of which is incorporated herein by reference thereto.
The devices described in U.S. Pat. Nos. 3,335,469 and 3,948,362 are a variety of "safety anchors" which comprise a tube through which a safety line is threaded and which has therein a wedge member and a line-gripping member. The tube is attached to the worker. Upon sudden downward acceleration, which occurs in the event of a fall, by inertia and or camming, the line gripping member in the tube is brought to bear against the wedge whereby the line gripping member engages the rope and further downward movement is prevented.
The fall protection devices of the prior art as specifically described above operate satisfactorily in most environments; however, where organic particulate matter is present as in a grain elevator, failure of the devices has been observed.
It was the observed failure of fall protection devices resembling those described in U.S. Pat. No. 3,948,362 which led to my development of the improved device wherein described and claimed.
Although not wishing to be bound it is believed that the observed failures resulted because particles in the environment collect and interfere with operation of the line gripping member preventing satisfactory engagement with the rope threaded through the tubular housing.
Detrimental accumulation can not be prevented by arrangements adapted to mask the openings through which the safety line is threaded. This is believed to indicate that accumulation and/or deposition in or upon the functioning components within the tubular housing may occur as a result of particulate matter transferred by the safety line which it is believed may have an enhanced attraction for suspended particulate matter due to a triboelectric effect associated with contact attendant to movement through the tubular housing.
The fall protection safety device of my invention which is suitable for use in environments wherein suspended particulate matter is present comprises an elongated tubular housing having an upper open end, a lower open end, and an elongate volume therebetween. An upper end guide block having a centrally located opening therein is secured to the upper open end of the housing. A lower end guide block having a centrally located opening therein and a plurality of openings spaced apart from and around the centrally located opening is secured to the lower end of the housing. The upper and lower end guide block openings define a central passageway through which a safety line is threaded. Within the tubular housing, a wedging ring having a centrally located conical bore is secured. A line-gripping means for gripping the safety line (threaded through the central passgeway and extending through the tubular housing) by movement upwardly within the conical bore of the wedging ring is located below the wedging ring. The line gripping means is associated with a piston also having a centrally located opening and a serrated outer surface adjacent to and circumscribed by the inner surface of the elongate tubular housing. The line-gripping means and associated piston are axially movable within the elongate tubular housing.
Means for moving a piston and associated line-gripping means upwardly within the conical bore of the wedging ring such as a cam and loop link arrangement are most suitable to engage the line-gripping means and safety line. A single link located at the lower portion of the tubular housing is most preferred for balance and worker attachment safety.